Pontiac Firebird - The Hemi Then And Now

'There's a ton of hoopla surrounding all things Hemi these days, and for good reason. While we can live without the investor types who revel in dollar signs instead of burning rubber and seven-grand power shifts, the Hemi renaissance-on the dragstrip, on the collector scene and in the show room-signals incredible times for horsepower junkies of all persuasions. You see, in the nearly half-decade since 2003 when Chrysler rekindled its Hemi legacy in the form of those potent 5.7- and 6.1L rear-wheel-drive trucks and cars, the war planners over at Ford and GM have been forced to take notice-and up the ante-just as they did in the '50s and '60s.

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The winner in all of this is the consumer who can now choose from more showroom stock horsepower and performance than ever before. Don't believe it? Then check into the specs of halo musclecar offerings like the Z06 (505 hp), GT500 KR (540 hp) or anything from the SRT8 family (425 hp with much more on tap) and you'll see bigger net horsepower ratings than even the biggest guns of the musclecar era. Beyond that, even the bread-and-butter light truck, SUV, and RWD V-8 passenger car consumer has more net horsepower to choose from than ever before. Heck, even the mainstream 5.7L Hemi is good for 340-350 horsepower (depending on tune). And remember, this is all net horsepower of the real-world variety. Not pie-in-the-sky, under-ideal-conditions popcorn like we used to get in decades past. So our hats go off to Chrysler for throwing another log on the fire and feeding the frenzy that continues to grow.

Some interesting parallels can be drawn between the new Hemi and the very first generation of Hemis that arrived way back in 1951. Back then Chrysler (and the rest of Detroit) was looking for a modern engine to carry its products into the postwar era. The mood was optimistic and everybody knew cars would be getting more luxurious and heavier with each passing season. Competing OHV V-8 designs generally employed strategies that banked heavily on the assumption that gasoline quality and supply-and octane rating-would continue to escalate, thanks to wartime advances made in petroleum refining and formulation.

As such, most of these post-WWII OHV V-8 designs-the '49 Olds 303 and Cadillac 331, '52 Lincoln 317 and Studebaker 233, '53 Buick 322, '54 Ford 239, '55 Packard 352, Pontiac 287 and Chevy 265 and '56 Nash 250-were built with the idea that they could rely on future compression ratio increases to add power as the market demanded it. Their (mostly) wedge-shaped combustion chamber designs were dependent on a steady diet of ever-increasing octane numbers to support compression-ratio growth. But over at Chrysler, the emphasis was on efficient breathing first, high compression second.

2/36The original '51-'58 Chrysler FirePower Hemi (Gen I) utilized cast-iron heads with fully machined 109cc combustion chambers, centrally located spark plugs, and an included valve angle of 58.5 degrees. Flat-top pistons delivered 7.5:1 compression. Note how the valves open toward the center of the bore away from the shrouding effects of the cylinder walls, and double rocker shafts actuate the valves.

Former Chrysler director of engineering and research James Zeder outlined the Chrysler strategy in a 1952 SAE report titled "New Horizons in Engine Development." He wrote, "The power of an engine should be based on physique, not on stimulants." In other words, the Chrysler design effort focused on volumetric efficiency and anti-detonation characteristics instead of sky-high compression to make power. By orienting the valves laterally within a hemispherical combustion chamber, the stems tipped outward so that when they opened, the valves plunged into the centers of the cylinder bores where they were not shrouded by the cylinder walls. This arrangement also paved the way for efficient ports with gentle short-side curves that also help flow. Of course this strategy can result in a particularly wide engine package and the expense of a double-rocker-shaft arrangement to actuate the valves. But at the time, low engine weight and compact girth weren't top priorities.

Unveiled in the '51 Chrysler line, the 331ci FirePower Hemi was an instant success. In mild two-barrel form it cranked out 180 hp, 20 more than its closest competitor, the 160hp wedgehead Cadillac 331. In the following seven years, the FirePower grew to 354 cubes (1956), then to 392 cubes (1957), and output of the top-dog, dual-quad 300D more than doubled to 380 hp by 1958. What's more, Hemi fever spread to DeSoto in 1952 with the 276ci Firedome and to Dodge in 1953 with the 241-cube Red Ram. The interesting parallel between then and now is that these Gen I Hemis were installed by the hundreds of thousands into everyday passenger cars and trucks, just like today's Gen III Hemis are. Sure, there were muscle models like the Chrysler 300, DeSoto Adventurer, and Dodge D500, but again, Hemi power was everywhere and you didn't have to spend much extra to get it.

The Gen I Chrysler, DeSoto, and Dodge Hemi powerplants are quickly identified by their rear-mounted distributors and were produced through 1958, when bean-counters finally caught up and determined that the cheaper-to-build polyspherical heads used on base model V-8s were just as effective for the job at hand. Another factor was the 1958 arrival of the 350ci B-series Chrysler big-block wedge and its later 361-, 383-, 413-, and 440-inch offspring. Truth be told, the new big-block wedges did everything the Hemis did just as well except when it came to ragged-edge power potential.

3/36The '64 (Gen II) 426 Hemi revival incorporated a 58-degree included valve angle, but the machined combustion chambers were slightly rotated toward the intake side of the head. This was done to reduce overall engine width for easier assembly-line body-drop activity. The 172cc combustion chamber volume required a large (and heavy) piston dome to yield high compression for race duty. Naysayers don't like to admit this isn't a "true" Hemi design. The vast majority of OE Hemi cylinder heads were cast iron except those aluminum heads installed on the approximately 201 A990 Super Stocks built in 1965. Currently, Gen II Hemi heads are widely available in both materials.

As drag racers had long since discovered, those Gen I Hemis, especially the big 392s from Chrysler, were capable of making four and even five times their original rated power when built for all-out competition. The problem was that all of this potential was wasted on the average consumer. And so the cheaper wedge took over. Until 1964, that is. Though the 413 and 426 wedges were potent enough to keep up with other new cars on the street and in mild drag competition, on the NASCAR superspeedways their heads offered no clearcut advantage over the competing 427 Fords and 421 Pontiacs. So in January 1963 Chrysler assigned Tom Hoover and a small team of underlings the task of melding the best features of the 392 Hemi and the 426 wedge into a single package with the intent of dominating the '64 Daytona 500. The result . . . drumroll please . . . was the fabled Gen II 426 Hemi, which is readily identified by its orange paint and front-mounted distributor.

We won't waste time covering the exploits of the 426 Hemi because you've probably heard it all before. Suffice it to say that starting with a one-two-three sweep at Daytona it has dominated virtually every form of sanctioned (and unsanctioned) competition and has rightfully gone down as one of the most significant American engine designs of all time-which brings us to the present. In these best of times, we can be thankful that the former DaimlerChrysler once again looked to its past when developing the current generation of Hemi powerplants. The strong demand for light trucks and SUVs was at the root of it, and when the so-called 5.7L Hemi Magnum was introduced as an option on '03 Dodge Ram trucks with its distinctive coil-on-plug crank trigger ignition, we all hoped it was just the beginning. We were not disappointed.

When development got started in 1997 the objective was to replace the obsolete LA-series 360 small-block in the upper end of the truck gasoline market. The 4.7L AMC-inspired V-8 was flawed by its compact bore spacing, so a clean-sheet approach was taken. According to SAE Technical Paper 2002-01-2815, "The New DaimlerChrysler Corporation 5.7L HEMI Engine," several non-Hemi possibilities were considered, including three and four valves per cylinder as well as single and dual overhead camshafts. But the paper concludes, "Ultimately, the two-valve, overhead valve hemispherical (Hemi) arrangement proved to be the best tradeoff."

In the five years since the 5.7L truck debut, musclecar fanatics have been overjoyed at the release of the rear-wheel-drive LX platform Chrysler C300, Dodge Magnum, and Dodge Charger, each with available 5.7L power and optional 6.1L SRT8 equipment. And let's not forget the thunder on the horizon-the '08 Challenger. Word is that we've only seen the beginning of what the Hemi can do, and there's buzz all over Detroit about all-aluminum 6.3L Hemis packing well over 500hp that are headed soon to a showroom near you. Camaro and Mustang, are you listening? A new ponycar performance war is in the works, and everybody wins. Let's take a walk through the world of Hemi and see what's happening.

Hemi Chamber ComparisonThere's a lot of hot air blowing around in some camps about whether the Gen III Hemi is actually a Hemi. Is Chrysler pulling a fast one here, or is the 5.7L/6.1L family a worthy successor to the dynasty of the Gen I and Gen II Hemis? We can settle the score right now with a look at each one.

426 Fashion ShowNo other powerplant in the automotive universe can wear so many hats and look great in every one of them. Here's a roundup of classic Hemi induction setups and build styles. Each one gives the burly beast an entirely different look. Try one on for size.

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If you're into the more traditional look of dual quads, go with an original dual-plane Street Hemi manifold-or the just-released MP reproduction of same. Then slap on a set of vintage Carter AFBs or Edelbrock Performers and you'll love how the dual carbs make the massive Hemi look so right. You can even go a step further and score a Stage V Engineering single-plane Rat Buster or MP eight-barrel (P4510633). Either one opens the door to the use of Holley carburetors-something the stock Street Hemi casting's close spacing can't handle. Rami Khory's '69 Charger R/T was born with an L-code 440 Magnum, but he's upgraded to this Rat Buster-fortified 540hp elephant by Submission Engines.

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A more hard-core NMCA outlaw vibe is possible when one of the new generation of single-plane manifolds is coupled with a Holley Dominator. This Stage V Engineering/ Ray Barton casting sits atop Kevin King's all-aluminum Hemi from Huntington Beach, California. Built by Submission Engines, this 572ci beast runs a Keith Black block, Stage V Engineering heads, and 12.5:1 slugs and makes 880 hp at 6,700 rpm. It powers King's street-legal '69 flip-nose Road Runner to low 9s in the quarter. Mondo single-plane Hemi intakes are also available from Indy Cylinder Head.

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The single four-barrel Hemi traces its roots back to the very first Track Hemis that swept the '64 Daytona 500 (NASCAR disallowed multiple carbs). While some feel a single carburetor gets lost between the Hemi's broad shoulders, the setup actually works very well on street and strip machinery like Steve Lowe's '68 Charger from Pomona. Steve's 528 crate Hemi still wears its box-stock M1 P4876188 dual-plane casting mounting a Holley 850. Further civility comes from a March serpentine pulley kit and real live air conditioning, something that was never offered on the '66-'71 Street Hemi when new.

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Some say the only proper Hemi induction is a cross-ram. Those cast for 1964 and 1968 factory race car packages are aluminum, while the 1965 A990 piece was lighter magnesium. Originals are scarce, but Rick Allison and the guys at A&A Transmission have been making faithful magnesium reproductions like this for several years. The whole point of the cross-ram layout is to take advantage of the naturally occurring resonant frequencies present in the intake tract when the valve opens and closes. The 12.4-inch total runner length is tuned to provide a slight supercharging effect above 5,000 rpm. The power and look are so popular that everything you see here, right down to the correct green return spring, is available in reproduction from A&A, Kramer Automotive Specialties, Mancini Racing, and others, so you no longer have to scrounge through piles of used-up race parts to get a cross-ram on your Hemi. More modern cross-ram designs are available from Indy Cylinder Head and Ray Barton for nonpurists.

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The cross-ram look has evolved radically through the years. While reworked stock castings-with the plenum tops cut off, then re-welded after internal mods were made-used to be the norm on class-legal Super Stock Hemi cars, NHRA finally allowed the use of fabricated intake manifolds as long as the carburetor centerlines are offset at least 1 inch. This is the class-legal SS/AH Hemi that powers Dave Raybourn's Mean Fish Hemi Barracuda from Modesto, California. Clearly its one-off intake is more of a tunnel-ram than a cross-ram, but it's part of the recipe for Raybourn's 8.63/153.3 performance. Unlike most modern SS/AH entries, this is a real '68 Hemi Barracuda. Wearing serial number BO29M8B299127, it was originally delivered to Pennsylvania drag racer Tom Myl back in 1968 and has been a drag car all its life. The VIN's second letter, O, stands for Super Stock. What other Detroit automaker was this cool?

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Now we're talking. In the '50s, Chrysler worked closely with Stu Hilborn and developed several direct-port mechanical fuel-injection setups that saw use on stock-block Indy car race engine and alcohol fuel projects. These experiments quickly spawned part numbers in the Hilborn catalog, and fuel-injected Gen I Hemis became a common-and feared-sight on strips across the nation. In 1965 Chrysler and Hilborn teamed up again on direct-port mechanical injection for the Gen II 426 Hemi to accommodate the use of alcohol and nitromethane in altered-wheelbase Funny Car applications. Today Hilborn, Crower, and Kinsler all offer these wicked setups in either mechanical or electronic modes. This Hilborn-equipped 472 Hemi has been fitted with electronic controls and runs sweet and smooth in traffic.

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For some, this is the only image that comes to mind when you say Hemi. No other engine looks so brutal with a Roots-type huffer bolted on top; some even look silly. Not the Hemi. The fact is, no other engine design is as capable of surviving in the world of Top Fuel like the Hemi. Just ask guys like John Force and Don Garlits if you need proof. This evil blown Hemi powers Sonny Wells' '71 Demon.

The Latest Hemi DevelopmentsThere aren't many factory guys who get their hands as dirty as Jon Clark. Jon, the department manager for Mopar Performance and Direct Connection brands, recently spent an entire week at renowned Hemi guru Ray Barton's Pennsylvania shop to make sure the latest Hemi block is as good as it can be.

Jon Clark is in charge of re-racking the entire Mopar Performance line and is especially proud of several new block, head, and intake manifold announcements. Included are compressed graphite blocks, a pure Street Hemi intake manifold reproduction, and enhanced A990 aluminum heads.

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Clark says the 392 Hemi crate program is taking off and there's plenty of cool stuff on the horizon. If all goes according to plan, he'll debut an all-aluminum Gen III 426 Hemi with dual-quad carburetors, a traditional distributor, and a mechanical fuel pump at the '07 SEMA show in Las Vegas. The block may (or may not) hint at what you'll find under the '08 Challenger's hood, while the distributor and mechanical fuel pump will be possible thanks to a new front cover casting. This is a 6.1L out of an SRT8 Charger. Dig the wild cast-aluminum barrel ram intake manifold. The spirit lives!

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Others present at the weeklong May 2007 Hemi dyno party were (from left to right) MP parts engineer Neil Loughlin, an unidentified Ray Barton employee, World Products' Bill Mitchell, and Ray Barton hisself. A longtime manufacturer of quality aftermarket Chevy engine blocks, Mitchell's World Products is collaborating with MP on new Hemi and wedge-block castings like the superbeefy iron version shown here. After assembly, this 528 Hemi block easily endured over 800 hp during the grueling validation process.

Groovy Factoids

* The peak year for 426 Street Hemi production was 1966, the inaugural year, with 2,729 units built. By contrast, only 356 Street Hemis were sold in 1971, the final year. The approximate total number of Street Hemi-powered cars built between 1966 and 1971 was 9,955.

* The rarest 426 Street Hemi-powered vehicle is the '70 Coronet R/T convertible. Only one was built (it still exists). The most common Street Hemi-powered vehicle is the '66 Plymouth Satellite hardtop; 817 were built. These are also the most affordable Street Hemis today with prices hovering between $70,000 and $90,000 for clean examples.

* Though certainly not promoted, the Street Hemi was available in four-door sedans in 1966. Approximately five are known to have been built, and a few still exist. A red '66 Coronet four-door Hemi recently sold at Barrett-Jackson for $660,000. No documented Hemi station wagons were built, though rumors persist. Show us one and we'll buy you a pizza.

* To meet a variety of NASCAR, ARCA, and NHRA rule changes over their racing career, factory-backed 426-style Hemis have been built with 366, 396, and 404ci displacements. The only displacement sold to the public was 426, though today you can also buy 472- and 528 ci Gen II crate Hemis from Mopar Performance.

* Chrysler's Saltillo, Mexico, engine plant is geared up to manufacture as many as 440,000 Gen III Hemis per year. Both the 5.7L and SRT8 6.1L are manufactured there.

* All 6.1L SRT8 Hemis have Hemi Orange paint on the block and aluminum "barrel-ram" intake manifolds. The bread-and-butter 5.7L Hemi is painted black and has a matching plastic intake manifold. Both haul ass.

When They Were CheapLet's fire up the time machine and travel back two decades to 1987 for a look at some cheap Hemi cars. OK, while a Hemi-powered anything could never be considered truly cheap-heck, they sold new for between 4,000 and 5,500 bucks, nearly the price of a luxury-packed Imperial-the astonishing price spike of the past decade makes these vintage asking prices seem like pocket change.

Hemi VIN Guide On all Street Hemi cars built between 1966 and 1971, the fifth digit of the VIN confirms Hemi status. Here are the codes, plus VIN data for the new breed of Gen III Hemi cars and light trucks. Remember, the '03-up VIN layout moves the engine code to the eighth position.